Power supply device

Abstract

To suppress a rush current while suppressing heat generation and reduction in efficiency.SOLUTION: A power supply device comprises: a DC-DC converter 3; a switch circuit 4 which switches an input DC voltage from the DC-DC converter 3; and a rush current suppression circuit 6 connected between the DC-DC converter 3 and the switch circuit 4. The rush current suppression circuit 6 comprises: a diode D5 which is interposed on a high potential line 61 and whose anode side is connected with the DC-DC converter 3; a resistive element R1 whose one end is connected with the high potential line 61 at a cathode side of the diode D5; a capacitor C1 whose one end is connected with the other end of the resistive element R1 and whose other end is connected with a low potential line 62; and a transistor Q which short-circuits the resistive element R1. The transistor Q short-circuits the resistive element R1 in a case where a voltage difference obtained by subtracting a voltage V1 at the anode side from a voltage V2 at the cathode side of the diode D5 becomes larger than a predetermined value (≥0 V).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power supply device that supplies a DC voltage to an inductive load. [Background technology]

[0002] Patent Document 1 discloses a power supply device that supplies a DC voltage to an electromagnet (inductive load) for deflecting and scanning a beam of charged particles emitted from an accelerator or the like. This power supply device includes a full-bridge circuit (switch circuit) that receives a DC voltage from a rectifier (DC source) and outputs a DC voltage to be supplied to the electromagnet. By controlling the full-bridge circuit, it is possible to adjust the amount of current output to the electromagnet and switch the polarity of the current. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-137243 Summary of the Invention [Problem to be solved by the invention]

[0004] In the case of the power supply device disclosed in Patent Document 1, when the load is an inductive load such as an electromagnet, if an abnormality occurs and the protection circuit is activated, causing the switch circuit to stop operating, the energy stored in the load is regenerated as induced electromotive force, and a regenerative current flows into the switch circuit.

[0005] One possible solution is to provide a capacitor with a capacitance corresponding to the load capacity between the DC source that supplies DC voltage to the switch circuit and the switch circuit, so that the regenerative current flows into the capacitor. However, if the capacitance of such a capacitor is increased, there is a risk that the charging current to the capacitor will become an inrush current when the DC source is started.

[0006] Therefore, it is necessary to place a resistive element to suppress the inrush current when the DC source is started. Such a resistive element is placed in series with the DC source between the DC source and the capacitor. Furthermore, by placing a switch element in parallel with such a resistive element, power loss in the resistive element can be avoided during normal operation after charging of the capacitor is completed. That is, by turning on the switch element and shorting the resistive element during normal operation, power loss in the resistive element can be avoided. However, such a switch element must be kept in the on state during normal operation. Therefore, the switch element becomes hot due to heat generation. Furthermore, the efficiency decreases due to the increased power consumption of the switch element.

[0007] The object of the present invention is to provide a power supply device that has the function of absorbing regenerative current from an inductive load that occurs when a protection circuit is activated in the event of an abnormality, causing the operation of a switch circuit to stop, and that can suppress inrush current while suppressing heat generation and efficiency reduction during normal operation. [Means for solving the problem]

[0008] The power supply device of the present invention is a power supply device that supplies a DC voltage to an inductive load, and includes a DC source, a switch circuit having a plurality of switch elements that switches an input DC voltage from the DC source using the plurality of switch elements, a DC converter circuit that converts an output voltage from the switch circuit into DC and supplies the converted DC voltage to the inductive load, and an inrush current suppression circuit connected between the DC source and the switch circuit, and the inrush current suppression circuit is interposed in a high potential line connecting a high potential output terminal of the DC source and a high potential input terminal of the switch circuit. a first diode having an anode connected to the high potential output terminal of the DC source; a resistive element having one end connected to the high potential line on the cathode side of the first diode; a capacitor having one end connected to the other end of the resistive element and the other end connected to a low potential line connecting the low potential output terminal of the DC source and the low potential input terminal of the switch circuit; and short-circuiting means for short-circuiting the resistive element when a voltage difference obtained by subtracting the voltage on the anode side from the voltage on the cathode side of the first diode exceeds a predetermined value that is 0 V or more.

[0009] During power supply, in which the input DC voltage from the DC source is supplied to the inductive load via the switch circuit and the DC converter, a forward current flows through the first diode, causing the voltage on the cathode side of the first diode to be lower than the voltage on the anode side by the forward voltage. That is, the voltage difference obtained by subtracting the voltage on the anode side from the voltage on the cathode side of the first diode is less than 0 V and less than a predetermined value. Therefore, during power supply, the shorting means does not short-circuit the resistive element. Therefore, when the DC source is started, the charging current to the capacitor flows while being limited by the resistive element, thereby suppressing inrush current. Because the resistive element is connected in series with the capacitor, no current flows through the resistive element during normal operation after the capacitor is fully charged. Therefore, power loss during normal operation due to the resistive element can be avoided.

[0010] Furthermore, when the protection circuit is activated due to an abnormality and the switch circuit stops operating, the energy stored in the inductive load is regenerated as an induced electromotive force, causing a regenerative current to flow from the output side to the input side of the switch circuit. Because this regenerative current flows in the reverse direction relative to the first diode, it does not flow through the first diode but instead flows into the capacitor via the resistive element. This increases the voltage on the cathode side of the first diode. When the voltage difference between the voltage on the cathode side of the first diode and the voltage on the anode side exceeds a predetermined value, the resistive element is short-circuited by the short-circuiting means. Short-circuiting the resistive element prevents the resistive element from interfering with the capacitor's absorption of regenerative energy. In this way, the short-circuiting means shorts the resistive element only when the switch circuit stops operating due to an abnormality. Therefore, compared to maintaining the resistive element shorted during normal operation, it is possible to suppress inrush current while minimizing heat generation and efficiency degradation.

[0011] In addition, in the above-mentioned power supply device, the short-circuiting means is a transistor connected in parallel with the resistance element, and the transistor has a first main electrode connected to the cathode side of the first diode, a second main electrode connected between the resistance element and the capacitor, and a control electrode conductively connected to the anode side of the first diode.

[0012] With this simple configuration, it is possible to realize a short-circuiting means that short-circuits the resistance element only when the operation of the switch circuit stops due to the occurrence of an abnormality.

[0013] Furthermore, in the above-described power supply device, the inrush current suppression circuit further includes a second diode between the control electrode and the high potential output terminal of the DC source, the cathode of which is conductively connected to the high potential output terminal of the DC source.

[0014] This configuration can prevent current from flowing from the high potential output terminal of the DC source to the control electrode of the transistor.

[0015] Additionally, in the above-described power supply device, the inrush current suppression circuit further includes a constant voltage diode between the control electrode and the anode side of the first diode, the cathode side of which is conductively connected to the control electrode.

[0016] According to this configuration, the short-circuiting means can prevent the resistance element from being short-circuited until the voltage difference obtained by subtracting the voltage on the anode side from the voltage on the cathode side of the first diode exceeds the Zener voltage of the constant voltage diode, thereby suppressing malfunction of the short-circuiting means.

[0017] Furthermore, in the above-described power supply device, the inrush current suppression circuit further includes a third diode connected in parallel to the resistive element, the anode side of which is connected to the one end of the capacitor.

[0018] With this configuration, after the regenerative current has stopped flowing, the abnormality disappears, and during normal operation the switch circuit resumes operation to supply power to the inductive load, allowing the power stored in the capacitor to be smoothly discharged via the third diode.

[0019] In the power supply device described above, the switch circuit is configured to be able to switch the polarity of the DC voltage to be output.

[0020] This configuration is suitable for supplying a DC voltage to an inductive load that requires the polarity of the supplied DC voltage to be switchable, such as a steering electromagnet. [Effects of the Invention]

[0021] According to the present invention, the protection circuit is activated in the event of an abnormality, thereby absorbing the regenerative current from the inductive load that occurs when the switch circuit stops operating, and the inrush current can be suppressed while suppressing heat generation and efficiency reduction during normal operation. [Brief explanation of the drawings]

[0022] [Figure 1]1 is a circuit diagram showing a configuration of a power supply device according to an embodiment of the present invention; [Figure 2] 2A and 2B are diagrams showing the switch circuit of FIG. 1, in which (a) shows the current flow in a first state under PWM control, and (b) shows the current flow in a second state under PWM control. [Figure 3] 2 is a diagram showing the switch circuit of FIG. 1, illustrating a state in which a regenerative current flows in from an inductive load. [Figure 4] FIG. 10 is a diagram showing a switch circuit of a power supply device according to a first modified example. [Figure 5] FIG. 10 is a diagram illustrating an inrush current suppression circuit of a power supply device according to a second modified example. DETAILED DESCRIPTION OF THE INVENTION

[0023] A preferred embodiment of the present invention will now be described with reference to the drawings.

[0024] (Circuit configuration of power supply unit 1) First, the circuit configuration of a power supply device 1 according to this embodiment will be described with reference to Figures 1 to 3. The power supply device 1 of this embodiment supplies a DC voltage to a steering electromagnet 2 that corrects the trajectory of a beam of charged particles in a synchrotron (circular accelerator). The power supply device 1 has a pair of output terminals T13, T14 to which the steering electromagnet 2, which is an inductive load, is connected. The power supply device 1 also mainly comprises a DC-DC converter 3, a switch circuit 4, a DC conversion circuit 5, an inrush current suppression circuit 6, and a control circuit 9.

[0025] The DC-DC converter 3 outputs a DC voltage. In other words, the DC-DC converter 3 corresponds to a DC source of the present invention. The DC-DC converter 3 of this embodiment is an insulated type. The high-potential input terminal T31 of the DC-DC converter 3 is connected to the input terminal T11, and the low-potential input terminal T32 is connected to the GND terminal T12. A DC voltage is applied between the input terminal T11 and the GND terminal T12 to the DC-DC converter 3. The DC-DC converter 3 steps up or steps down the input DC voltage and outputs it.

[0026] The switch circuit 4 receives the DC voltage output from the DC-DC converter 3. A high potential input terminal T41 of the switch circuit 4 is connected to a high potential output terminal T33 of the DC-DC converter 3 by a high potential line 61. A low potential input terminal T42 of the switch circuit 4 is connected to a low potential output terminal T34 of the DC-DC converter 3 by a low potential line 62.

[0027] The high-potential output terminal T43 of the switch circuit 4 is connected to the output terminal T13 by a wiring 81. A coil L1 is interposed in the wiring 81. The low-potential output terminal T44 of the switch circuit 4 is connected to the output terminal T14 by a wiring 82. The DC converter circuit 5 is connected between the output terminals T43, T44 and the output terminals T13, T14.

[0028] As shown in FIG. 2, the switch circuit 4 is a full-bridge circuit in which four switch elements S1 to S4 are bridge-connected. The switch circuit 4 switches the input DC voltage from the DC-DC converter 3 using these switch elements S1 to S4. The switch circuit 4 is configured to be able to switch the polarity of the output DC voltage. The switch elements S1 to S4 are configured with semiconductor devices such as IGBTs and FETs. In this embodiment, the switch elements S1 to S4 are N-channel IGBTs. The four switch elements S1 to S4 are provided with freewheeling diodes D1 to D4, respectively. If the switch elements are FETs, the internal body diodes can be used as freewheeling diodes.

[0029] One end of wire 71 is connected to high potential input terminal T41, and the other end branches into wires 73 and 74. The end of wire 73 opposite to wire 71 is connected to the collector of switch element S1. The end of wire 74 opposite to wire 71 is connected to the collector of switch element S3.

[0030] One end of wire 72 is connected to low potential input terminal T42, and the other end branches into wires 75 and 76. The end of wire 75 opposite to wire 72 is connected to the emitter of switch element S2. The end of wire 76 opposite to wire 72 is connected to the emitter of switch element S4.

[0031] The emitter of switch element S1 and the collector of switch element S2 are connected by a wire 77. That is, switch element S1 and switch element S2 are connected in series. One end of a wire 79 is connected to the middle of wire 77. The other end of wire 79 is connected to high-potential output terminal T43.

[0032] The emitter of switch element S3 and the collector of switch element S4 are connected by a wire 78. That is, switch element S3 and switch element S4 are connected in series. One end of a wire 80 is connected to the middle of wire 78. The other end of wire 80 is connected to low potential output terminal T44.

[0033] As shown in FIG. 1, a DC converter circuit 5 is connected between a pair of output terminals T43, T44 of the switch circuit 4 and output terminals T13, T14 to which the steering electromagnet 2 is connected. The DC converter circuit 5 converts the output voltage from the switch circuit 4 into a DC signal and supplies the DC signal to the steering electromagnet 2. The DC converter circuit 5 is an LC high-frequency filter made up of a coil L1 and a capacitor C2. The DC converter circuit 5 attenuates current ripple caused by the switching of the switch elements S1 to S4. In FIG. 1, the coil L1 constituting the DC converter circuit 5 is provided between the output terminal T43 and the output terminal T13. However, the coil L1 may be provided interposed in the wiring 82 connecting the output terminal T44 and the output terminal T14.

[0034] A capacitor C3 is disposed between the high potential line 61 and the low potential line 62. One end of a wiring 83 is connected to the high potential line 61, and the other end of the wiring 83 is connected to one end of the capacitor C3. One end of a wiring 84 is connected to the low potential line 62, and the other end of the wiring 84 is connected to the other end of the capacitor C3. The capacitor C3 can stabilize noise from the switch circuit 4.

[0035] The switch circuit 4 is controlled by a control circuit 9. The control circuit 9 performs PWM control on the switch elements S1 and S2 to adjust the amount of current output from the switch circuit 4. The control circuit 9 also performs on / off control on the switch elements S3 and S4 to switch the polarity of the current output from the switch circuit 4.

[0036] In FIGS. 2(a) and 2(b), switch element S3 is OFF and switch element S4 is ON. At this time, the polarity of the current output from switch circuit 4 is positive. In PWM control, switching is performed between the ON state (first state) shown in FIG. 2(a) and the OFF state (second state) shown in FIG. 2(b). In FIGS. 2(a) and 2(b), the direction of current flow is indicated by the two-dot chain arrow. As shown in FIG. 2(a), in the ON state, switch element S1 is ON and switch element S2 is OFF. As shown in FIG. 2(b), in the OFF state, switch element S1 is OFF and switch element S2 is ON. In PWM control, the amount of current output from switch circuit 4 is adjusted by changing the duration (duty) of the ON state.

[0037] Furthermore, by turning switch element S3 ON and switch element S4 OFF, the polarity of the current output from switch circuit 4 can be made negative. In this case, in PWM control, turning switch element S1 OFF and switch element S2 ON results in an ON state (first state), and turning switch element S1 ON and switch element S2 OFF results in an OFF state (second state).

[0038] Here, with reference to Figure 3, we will explain what happens when a protection circuit such as an output overcurrent protection circuit or an overvoltage protection circuit of the switch circuit 4 is activated when an abnormality occurs, causing the operation of the switch circuit 4 to stop. In Figure 3, the direction of current flow is indicated by a two-dot chain arrow. When the protection circuit is activated, all of the switch elements S1 to S4 are turned OFF. At this time, the energy stored in the steering electromagnet 2 is regenerated as an induced electromotive force. The regenerated current flows from the output side to the input side of the switch circuit 4 via the freewheeling diodes D2 and D3 of the switch circuit 4, and flows into a capacitor C1, which will be described in detail later.

[0039] Returning to Fig. 1, the inrush current suppression circuit 6 is connected between the DC-DC converter 3 and the switch circuit 4. The inrush current suppression circuit 6 mainly includes a diode D5, a resistor R1, a capacitor C1, a transistor Q, a constant voltage diode ZD, a diode D6, and a diode D7.

[0040] Diode D5 is inserted in high potential line 61 connecting high potential output terminal T33 of DC-DC converter 3 and high potential input terminal T41 of switch circuit 4. The anode side of diode D5 is connected to high potential output terminal T33 of DC-DC converter 3. Diode D5 prevents the regenerative current from flowing into high potential output terminal T33 of DC-DC converter 3.

[0041] One end of the resistor R1 is connected to the cathode side of the diode D5 and to the high potential line 61. More specifically, one end of the resistor R1 is connected to the other end of a wiring 92 that branches off from the high potential line 61 between the connection portion with the wiring 83 and the diode D5.

[0042] The positive electrode of the capacitor C1 is connected to the other end of the resistor R1 by a wiring 93. The negative electrode of the capacitor C1 is connected to the low potential line 62.

[0043] Capacitor C1 has a capacitance corresponding to the capacitance of steering electromagnet 2. When the operation of switch circuit 4 stops due to the occurrence of an abnormality, regenerative energy from steering electromagnet 2 can be stored in capacitor C1. Note that regenerative energy is also stored in capacitor C3. However, the capacitance of capacitor C1 is sufficiently larger than that of capacitor C3, so regenerative energy is mainly stored in capacitor C1.

[0044] If the capacitance of capacitor C1 is large, the charging current to capacitor C1 may become an inrush current when DC-DC converter 3 starts up, which may trip the overcurrent protection circuit of DC-DC converter 3. If the overcurrent protection method is a stopping operation such as output shutdown stopping operation or intermittent stopping operation, there is a possibility that startup will not be successful. Inrush current suppression circuit 6 is a circuit that suppresses this inrush current.

[0045] The transistor Q is a PNP transistor connected in parallel with the resistor R1. The transistor Q can short-circuit the resistor R1. The emitter of the transistor Q (corresponding to the "first main electrode" of the present invention) is connected to the cathode side of the diode D5. The collector of the transistor Q (corresponding to the "second main electrode" of the present invention) is connected between the resistor R1 and the capacitor C1. The base of the transistor Q (corresponding to the "control electrode" of the present invention) is conductively connected to the anode side of the diode D5 via the base resistor R2, the zener diode ZD, and the diode D6.

[0046] One end of a wire 94 is connected to the middle of the wire 92, and the other end is connected to the emitter of the transistor Q. One end of a wire 95 is connected to the middle of the wire 93, and the other end is connected to the collector of the transistor Q. One end of a wire 96 is connected to a portion of the high-potential line 61 between the high-potential output terminal T33 of the DC-DC converter 3 and the diode D5, and the other end is connected to the base of the transistor Q.

[0047] A base resistor R2 of the transistor Q is interposed in the wiring 96. A base-emitter resistor R3 of the transistor Q is interposed in a wiring 97 having one end connected to a portion of the wiring 96 between the base of the transistor Q and the base resistor R2 and the other end connected to the middle of the wiring 94.

[0048] Diode D6 is arranged between the base of transistor Q and high potential output terminal T33 of DC-DC converter 3. Diode D6 is arranged in a portion of wiring 96 between a connection portion with high potential line 61 and base resistor R2. The cathode side of diode D6 is conductively connected to high potential output terminal T33 of DC-DC converter 3.

[0049] The voltage regulator diode ZD is disposed between the base of the transistor Q and the anode side of the diode D5. The voltage regulator diode ZD is disposed in a portion of the wiring 96 between the diode D6 and the base resistor R2. The cathode side of the voltage regulator diode ZD is conductively connected to the base of the transistor Q via the base resistor R2.

[0050] Diode D7 is connected in parallel with resistor R1. One end of diode D7 is connected to the middle of wiring 92, and the other end is disposed on wiring 98 that is connected to the middle of wiring 93. The anode side of diode D7 is connected to the positive electrode of capacitor C1.

[0051] (Operation of inrush current suppression circuit 6) Next, the operation of the inrush current suppression circuit 6 will be described. First, consider the time when power is supplied, in which a DC voltage from the DC-DC converter 3 is output to the steering electromagnet 2 via the switch circuit 4 and the DC conversion circuit 5. When power is supplied, a forward current flows through the diode D5, so the voltage V2 between the cathode side of the diode D5 and GND is lower than the voltage V1 on the anode side of the diode D5 by the amount of the forward voltage. In other words, the voltage applied to the base of the transistor Q is a positive voltage with respect to the emitter. Therefore, when power is supplied, the transistor Q is in the OFF state, and the resistor R1 is not short-circuited by the transistor Q.

[0052] Therefore, when the DC-DC converter 3 starts up, the charging current to the capacitor C1 flows while being limited by the resistor element R1, thereby suppressing the inrush current. Because the resistor element R1 is connected in series with the capacitor C1, no current flows through the resistor element R1 during normal operation after charging of the capacitor C1 is completed. Therefore, power loss in the resistor element R1 during normal operation can be avoided.

[0053] Next, consider the case where the switch circuit stops operating due to an abnormality. At this time, regenerative current from the steering electromagnet 2 flows from the output side to the input side of the switch circuit 4. Since this regenerative current flows in the opposite direction to diode D5, it does not flow into diode D5, but instead flows into capacitor C1 via resistor R1. This causes voltage V2 on the cathode side of diode D5 to rise. When the voltage difference obtained by subtracting the voltage V1 on the anode side from the voltage V2 on the cathode side of diode D5 exceeds the Zener voltage Vz of the constant voltage diode ZD, transistor Q switches from OFF to ON. With transistor Q in the ON state, resistor R1 is shorted by transistor Q.

[0054] That is, the transistor Q is connected to the anode side voltage V1 of the diode D5, the cathode side voltage V2 of the diode D5, and the Zener voltage Vz(0<Vz)が、V2‐V1> When the Vz relationship is satisfied, the resistor element R1 is short-circuited to the ON state.

[0055] When the transistor Q switches from OFF to ON, the resistor element R1 is short-circuited, which prevents the resistor element R1 from hindering the absorption of regenerative energy into the capacitor C1.

[0056] After the regenerative current from the steering electromagnet 2 has finished flowing, the charge accumulated in the capacitor C1 is smoothly discharged via the diode D7 during normal operation when the switch circuit 4 resumes operation and supplies power to the steering electromagnet 2.

[0057] (Features of the embodiment) As described above, the power supply device 1 of this embodiment is a power supply device 1 that supplies a DC voltage to the steering electromagnet 2, which is an inductive load, and includes a DC-DC converter 3, a switch circuit 4 having a plurality of switch elements S1 to S4 that switches the input DC voltage from the DC-DC converter 3 using the switch elements S1 to S4, a DC conversion circuit 5 that converts the output voltage from the switch circuit 4 into DC and supplies it to the steering electromagnet 2, and an inrush current suppression circuit 6 connected between the DC-DC converter 3 and the switch circuit 4. The inrush current suppression circuit 6 is disposed on a high-potential line 61 connecting the high-potential output terminal T33 of the DC-DC converter 3 and the high-potential input terminal T41 of the switch circuit 4, and includes a diode D5 having an anode connected to the high-potential output terminal T33 of the DC-DC converter 3, a resistive element R1 having one end connected to the high-potential line 61 on the cathode side of the diode D5, a capacitor C1 having one end connected to the other end of the resistive element R1 and the other end connected to a low-potential line 62 connecting the low-potential output terminal T34 of the DC-DC converter 3 and the low-potential input terminal T42 of the switch circuit 4, and a transistor Q that shorts out the resistive element R1 when the voltage difference obtained by subtracting the anode-side voltage V1 from the cathode-side voltage V2 of the diode D5 exceeds a predetermined value (Zener voltage Vz) that is 0 V or more.

[0058] During power supply, the voltage difference obtained by subtracting the anode voltage V1 from the cathode voltage V2 of diode D5 is less than a predetermined value (Zener voltage Vz). Therefore, during power supply, transistor Q does not short-circuit resistor R1. Therefore, when DC-DC converter 3 starts up, the charging current to capacitor C1 is limited by resistor R1, thereby suppressing inrush current. Because resistor R1 is connected in series with capacitor C1, no current flows through resistor R1 during normal operation after charging of capacitor C1 is completed. Therefore, power loss during normal operation in resistor R1 can be avoided.

[0059] Furthermore, when the protection circuit is activated due to an abnormality, the regenerative current from the steering electromagnet 2, which occurs when the switch circuit 4 stops operating, flows in the opposite direction to the diode D5. Therefore, the current does not flow through the diode D5, but instead flows into the capacitor C1 via the resistor R1. This causes the voltage V2 on the cathode side of the diode D5 to rise. When the voltage difference obtained by subtracting the voltage V1 on the anode side from the voltage V2 on the cathode side of the diode D5 exceeds a predetermined value (Zener voltage Vz), the resistor R1 is short-circuited by the transistor Q. Shorting the resistor R1 prevents the resistor R1 from interfering with the regenerative energy absorption effect of the capacitor C1. In this way, the transistor Q shorts the resistor R1 only when the switch circuit stops operating due to an abnormality. Therefore, compared to maintaining the resistor R1 shorted during normal operation, the inrush current can be suppressed while suppressing heat generation and efficiency degradation.

[0060] In the power supply device 1 of this embodiment, the transistor Q is a PNP transistor connected in parallel with the resistor R1, with its emitter connected to the cathode of the diode D5, its collector connected between the resistor R1 and the capacitor C1, and its base conductively connected to the anode of the diode D5. This simple configuration makes it possible to realize a short-circuiting means that shorts the resistor R1 only when the operation of the switch circuit 4 stops due to the occurrence of an abnormality.

[0061] In the power supply device 1 of this embodiment, the inrush current suppression circuit 6 further includes a diode D6, the cathode of which is conductively connected to the high potential output terminal T33 of the DC-DC converter 3, between the base of the transistor Q and the high potential output terminal T33 of the DC-DC converter 3. This configuration makes it possible to prevent current from flowing from the high potential output terminal T33 of the DC-DC converter 3 toward the base of the transistor Q.

[0062] In the power supply device 1 of this embodiment, the inrush current suppression circuit 6 further includes a constant voltage diode ZD, which is disposed between the base of the transistor Q and the anode of the diode D5 and has its cathode conductively connected to the base of the transistor Q. This configuration prevents the transistor Q from shorting out the resistor element R1 until the voltage difference obtained by subtracting the anode voltage V1 from the cathode voltage V2 of the diode D5 exceeds the Zener voltage Vz of the constant voltage diode ZD, thereby suppressing malfunction of the transistor Q.

[0063] In the power supply device 1 of this embodiment, the inrush current suppression circuit 6 further includes a diode D7 connected in parallel to the resistance element R1 and having an anode connected to the positive electrode of the capacitor C1. With this configuration, after the regenerative current stops flowing, the abnormality disappears, the switch circuit 4 resumes operation, and during normal operation when power is supplied to the steering electromagnet 2, the power accumulated in the capacitor C1 can be smoothly discharged via the diode D7.

[0064] In the power supply device 1 of this embodiment, the switch circuit 4 is configured to be able to switch the polarity of the DC voltage to be output. This configuration is suitable for supplying a DC voltage to an inductive load that requires the polarity of the supplied DC voltage to be switchable, such as the steering electromagnet 2.

[0065] Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to these embodiments. The scope of the present invention is defined by the claims rather than the description of the above embodiments, and further includes all modifications within the meaning and scope of the claims.

[0066] In the above-described embodiment, the case where the switch circuit 4 is configured to be able to switch the polarity of the DC voltage it outputs has been described, but the present invention is not limited to this. That is, as shown in FIG. 4 , a switch circuit 4A of a power supply device according to a first modification of the present embodiment has switch elements S1, S2, and S4 and freewheeling diodes D1, D2, and D4 similar to those of the switch circuit 4. In the switch circuit 4A, the end of the wiring 74 opposite to the wiring 71 side is connected to the collector of the switch element S4. A diode D13 is also interposed in the wiring 74. The cathode of the diode D13 is connected to the high-potential input terminal T41.

[0067] In the switch circuit 4A as well, the control circuit 9 performs PWM control on the switch elements S1 and S2, thereby adjusting the amount of current output from the switch circuit 4A. Also in the switch circuit 4A, the regenerative current from the steering electromagnet 2 flows from the output side to the input side of the switch circuit 4A via the freewheeling diode D2 and diode D13 of the switch circuit 4A, and then flows into the capacitor C1.

[0068] In the above embodiment, a PNP transistor Q connected in parallel with the resistor R1 is used as short-circuiting means for short-circuiting the resistor R1, but the present invention is not limited to this. That is, as shown in Fig. 5, in an inrush current suppression circuit 6A of a power supply device according to a second modification of the present embodiment, a P-channel FET transistor Q0 connected in parallel with the resistor R1 is used as short-circuiting means.

[0069] The transistor Q0 has a first main electrode, that is, a source, connected to the cathode side of the diode D5, a second main electrode, that is, a drain, connected between the resistor element R1 and the capacitor C1, and a control electrode, that is, a gate, conductively connected to the anode side of the diode D5.

[0070] When the transistor Q0 is used as the short-circuiting means, similarly to the transistor Q, the resistance element R1 can be short-circuited when the voltage difference obtained by subtracting the anode side voltage V1 from the cathode side voltage V2 of the diode D5 exceeds a predetermined value (Zener voltage Vz) that is equal to or greater than 0 V. Therefore, with a simple configuration, it is possible to realize a short-circuiting means that short-circuits the resistance element R1 only when the operation of the switch circuit 4 stops due to the occurrence of an abnormality.

[0071] Furthermore, in the above embodiment, the case where the diode D6 is arranged between the base of the transistor Q and the high potential output terminal T33 of the DC-DC converter 3 has been described, but the diode D6 may be omitted.

[0072] Additionally, in the above-described embodiment, the case where the zener diode ZD is disposed between the diode D6 and the base resistor R2 has been described, but this is not limiting. The zener diode ZD may be disposed between the base of the transistor Q and the anode side of the diode D5. The zener diode ZD may also be omitted. If the zener diode ZD is not disposed, the transistor Q shorts out the resistor element R1 when the voltage difference obtained by subtracting the voltage V1 on the anode side from the voltage V2 on the cathode side of the diode D5 exceeds 0 V, i.e., when V2 > V1.

[0073] Additionally, in the above embodiment, the case where the diode D7 connected in parallel with the resistance element R1 is disposed has been described, but the diode D7 may be omitted.

[0074] In the above embodiment, the DC source that outputs the DC voltage is an insulated DC-DC converter 3, but this is not limiting. That is, the DC source may be a non-insulated DC-DC converter. Furthermore, the DC source may also be a battery (lithium ion battery, nickel-metal hydride battery, etc.), a battery (storage battery), a solar cell, a fuel cell, an AC-DC converter, etc.

[0075] Furthermore, in the above embodiment, the load is the steering electromagnet 2, but the present invention is not limited to this. The present invention is applicable to all power supply devices that supply DC voltage to an inductive load. [Explanation of symbols]

[0076] 1 Power supply 2 Steering electromagnet (inductive load) 3 DC-DC converter (DC source) 4 Switch Circuit 5 DC conversion circuit 6 Inrush current suppression circuit 61 High voltage line 62 Low voltage line C1 capacitor D1~D4 Freewheeling diodes D5 Diode (first diode) D6 Diode (second diode) D7 Diode (third diode) Q Transistor (Short circuit, PNP type transistor) Q0 transistor (short circuit, Pch FET) R1 Resistor element S1~S4 Switch elements T33 High potential output terminal T34 Low potential output terminal T41 High potential input terminal T42 Low potential input terminal ZD Constant voltage diode

Claims

1. A power supply device that supplies a DC voltage to an inductive load, a direct current source; a switch circuit having a plurality of switch elements for switching an input DC voltage from the DC source by the plurality of switch elements; a DC converter circuit that converts the output voltage from the switch circuit into a DC voltage and supplies the DC voltage to the inductive load; an inrush current suppression circuit connected between the DC source and the switch circuit; Equipped with The inrush current suppression circuit includes: a first diode interposed in a high potential line connecting a high potential output terminal of the DC source and a high potential input terminal of the switch circuit, the anode side of the first diode being connected to the high potential output terminal of the DC source; a resistor element having one end connected to the high potential line on the cathode side of the first diode; a capacitor having one end connected to the other end of the resistor element and the other end connected to a low potential line connecting a low potential output terminal of the DC source and a low potential input terminal of the switch circuit; and short-circuiting means for short-circuiting the resistance element when a voltage difference obtained by subtracting the voltage on the anode side from the voltage on the cathode side of the first diode exceeds a predetermined value that is 0 V or more.

2. the short-circuiting means is a transistor connected in parallel with the resistance element, 2. The power supply device according to claim 1, wherein the transistor has a first main electrode connected to the cathode side of the first diode, a second main electrode connected between the resistance element and the capacitor, and a control electrode conductively connected to the anode side of the first diode.

3. The inrush current suppression circuit includes:

3. The power supply device according to claim 2, further comprising a second diode between the control electrode and the high potential output terminal of the DC source, the cathode of which is conductively connected to the high potential output terminal of the DC source.

4. The inrush current suppression circuit includes:

3. The power supply device according to claim 2, further comprising a constant voltage diode between the control electrode and the anode side of the first diode, the cathode side of which is conductively connected to the control electrode.

5. The inrush current suppression circuit includes:

2. The power supply device according to claim 1, further comprising a third diode connected in parallel with the resistance element, the anode of the third diode being connected to the one end of the capacitor.

6. 6. The power supply device according to claim 1, wherein the switch circuit is configured to be able to switch the polarity of the DC voltage supplied to the inductive load.

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